NEW CONCEPTS FOR DESIGNING BRIDGE APPROACH SLABS

The well-known bump-at-the-end-of-the-bridge often involves the joint between the bridge approach slab (BAS) and a bridge deck as the root cause has been a recurring nationwide issue over the years. DOTs have reported that the roughness and the associated slab cracking near this joint have significantly reduced ride quality. Recent field investigations have found that similar problems can also develop at the BAS – pavement joint due to erosion that has taken place underneath it. Considerations are provided in this paper with respect to how potential erosion could be better addressed by addressing the factors that affect it in the design of the BAS thickness. An approach previously developed by the research team is briefly introduced to facilitate the prediction of erosion damage occurring underneath the BAS – pavement joint. As a means to improve the current methodology for designing the thickness of BASs, this paper elaborates a modified mechanistic – empirical design procedure using a an “erosion-based slab thickness” concept to account for the effect of the erosion damage on the structural capacity of the BAS; reliability considerations with respect to the cracking performance of BASs are also provided to facilitate the design process.